OK, this is not an immediate need for help as I have come up with a workaround, but hopefully you will agree that it still needs fixing. I'm going to try and fully describe what I found, so here goes:
I'm using the OceanWP theme and displaying a Posts View in a my main menu by using the themes ability to show a widget area as a MegaMenu. Basically, I dropped a WP Views widget into a custom widget area, then added that widget area to my menu. You can see this at hidden link by hovering over the "What's New?" menu item. It is the list on the right.
It was working great until I applied the 2.5.1 Views update, then I began getting this error above the list, repeated once for every post item returned by the view:
Warning: Missing argument 2 for OE_Menu_Icons_Front_End::_add_icon() in /home/sbvfdtx/public_html/wp-content/plugins/ocean-extra/includes/menu-icons/includes/front.php on line 156
I included a screenshot of the problem with this ticket.
I changed various things about the view, deleted and re-created the view, the widget area, the menu, etc., all to no avail. I eventually discovered that any POSTS view I created (no matter how simple) did the same thing, but USER views did not have the problem. But obviously I need this specific posts view to work, so I dug deeper.
I tried replacing the WP Views widget with a basic HTML widget containing the view shortcode, with no immediate luck. Then I began to suspect that since I essentially get two "items" (the error message and the correct rendering) for each post returned, maybe the issue is related to the query portion of the view. In the Filter and Loop Output Integration Editor of the view, I added hide="true" as follows:
[wpv-filter-meta-html hide="true"]
This worked - as long as I leave the HTML widget in my menu. If I revert to the WP Views widget, the error returns (even with the hide="true" statement).
So, I have the site functioning correctly for now, but still would appreciate a resolution so that I can use the full functionality of my Views plugin without workarounds. Sorry to be so long-winded, but I'm hoping that my tinkering will help point you more directly to the source of the issue and help with a fix.
Thanks!
Don